Polypropylene filter for central supply, which I have been using for about 1 year after using similar thread filters and ceramic filters (always central supply). It is slightly more expensive than the corresponding polypropylene thread filters (for particles and suspensions in water) and of course cheaper than the corresponding washable ceramic (stone) filter, which has a theoretical lifespan of 2-3 years. I am not knowledgeable about the subject, but I ended up with this one because the visual result of water filtration was clearly clearer in this one compared to the other one with polypropylene fibers. In other words, although the description suggests changing every 3-6 months, the filter (obviously due to water quality) "darkens" after 1 month (!) and needs to be replaced... I consider that it does a good job even when used in combination with a countertop filter inside the installation...